Encrypt like the Romans and the Victorians: Caesar shifts, Atbash mirrors, ROT13 and the Vigenère key cipher. Then watch the “crack” button undo a Caesar cipher in one click — because letter frequency never lies.
Caesar shifts every letter by a fixed amount (Julius Caesar used 3). Atbash mirrors the alphabet (A↔Z). ROT13 is a Caesar-13, its own inverse. Vigenère shifts each letter by a repeating keyword, which defeated frequency analysis for 300 years — until Babbage broke it. The crack button only works on Caesar because a fixed shift leaves the letter-frequency fingerprint intact.